STABLE CERIUM-ZIRCONIUM SOLID SOLUTION AND PREPARATION METHOD THEREFOR AND APPLICATION THEREOF

Abstract

Disclosed are a cerium-zirconium solid solution and a preparation method therefor and an application thereof, which belong to the field of adsorbing catalyst materials. The cerium-zirconium solid solution includes a cerium-zirconium solid solution phase with a Ce.sup.3+/Ce.sup.4+ molar ratio of 0.05-0.8:1. The cerium-zirconium solid solution phase in the cerium-zirconium solid solution of the present application includes trivalent cerium ions and tetravalent cerium ions in a specific ratio. The cerium-zirconium solid solution has a high oxygen storage and release rate, a high oxygen storage and release capacity, and the cerium-zirconium solid solution during the storage and release of oxygen has a stable structure and good catalytic performance; and the catalyst containing the cerium-zirconium solid solution has good catalytic performance under different fuel ratios.

Claims

1-10. (canceled)

11. A cerium-zirconium solid solution, comprising a cerium-zirconium solid solution phase, wherein the cerium-zirconium solid solution phase comprises trivalent cerium ions and tetravalent cerium ions, a molar ratio of the trivalent cerium ions to the tetravalent cerium ions being 0.05-0.8:1.

12. The cerium-zirconium solid solution according to claim 11, wherein the molar ratio of the trivalent cerium ions to the tetravalent cerium ions is 0.1-0.5:1.

13. The cerium-zirconium solid solution according to claim 11, wherein the cerium-zirconium solid solution comprises a cerium oxide, ZrO.sub.2, and a first rare earth element oxide in a weight ratio of 20-50:20-80:2-20; wherein the first rare earth element is selected from at least one of rare earth elements other than cerium, transition metal elements, and alkaline earth metal elements.

14. The cerium-zirconium solid solution according to claim 13, wherein the first rare earth element is selected from at least one of lanthanum, yttrium, praseodymium, neodymium, and samarium.

15. The cerium-zirconium solid solution according to claim 13, wherein the cerium-zirconium solid solution further comprises a second rare earth element oxide, the weight ratio of the cerium oxide to the second rare earth oxide being 20-50:2-5; wherein the second rare earth element is selected from at least one of promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and scandium.

16. The cerium-zirconium solid solution according to claim 13, wherein the cerium-zirconium solid solution comprises a cerium oxide, ZrO.sub.2, a first rare earth element oxide, and a second rare earth element oxide in a weight ratio of 25-45:30-70:3-15:2-4.

17. The cerium-zirconium solid solution according to claim 11, wherein after calcination at 850° C. for 4 hours, an oxygen storage capacity of the cerium-zirconium solid solution is not less than 540 μmol [O]/g; and/or a specific surface area of the cerium-zirconium solid solution treated at 1100° C. for 4 hours is not less than 30 m.sup.2/g.

18. A preparation method for the cerium-zirconium solid solution according to claim 11, comprising the following steps: 1) mixing: preparing an initial mixture of an aqueous solution containing trivalent cerium ions and zirconium ions; 2) oxidation reaction: adding hydrogen peroxide to the acidic initial mixture according to a required amount of trivalent cerium ions and tetravalent cerium ions, and adding a precipitant to adjust pH of the solution to 10-11 to obtain a precursor solution; 3) a first hydrothermal reaction: after the first hydrothermal reaction, calcining the precursor solution in an inert gas to obtain the cerium-zirconium solid solution.

19. The preparation method for the cerium-zirconium solid solution according to claim 18, wherein the mixing in the step 1) comprises the step of: preparing an initial mixture of an aqueous solution containing trivalent cerium ions, zirconium ions and M ions; wherein the M element is selected from at least one of rare earth elements other than cerium, transition metal elements, and alkaline earth metal elements.

20. The preparation method for the cerium-zirconium solid solution according to claim 18, wherein the step 2) comprises the following steps: {circle around (1)} adding an alkaline precipitant to the initial mixture until the pH of the solution is 1.0-2.5; adding 30% of an aqueous solution of hydrogen peroxide to the acidic initial mixture according to the amount of trivalent cerium ions and tetravalent cerium ions, and stirring at least 1 hour for a second hydrothermal reaction; and {circle around (2)} adding a precipitant to adjust the pH of the solution to 10-11, and aging the solution for at least 1 hour to obtain the precursor solution.

21. The preparation method for the cerium-zirconium solid solution according to claim 18, wherein a calcining condition in the step 3) is calcining in an inert gas at 750° C.-850° C. for 4 hours.

22. The preparation method for the cerium-zirconium solid solution according to claim 18, wherein the cerium-zirconium solid solution comprises 20 wt %-60 wt % cerium oxide and 35 wt %-60 wt % ZrO.sub.2, and the cerium oxide comprises trivalent cerium ions and tetravalent cerium ions in a molar ratio of 0.05-0.7:1.

23. A catalyst, comprising a cerium-zirconium solid solution, wherein the cerium-zirconium solid solution is selected from: the cerium-zirconium solid solution according to claim 1, or the cerium-zirconium solid solution according to claim 1 calcined at 500-1200° C. for at least 1 hour.

24. A catalyst, comprising a cerium-zirconium solid solution, wherein the cerium-zirconium solid solution is selected from: the cerium-zirconium solid solution prepared by the method according to claim 18, or the cerium-zirconium solid solution prepared by the method according to claim 18 calcined at 500-1200° C. for at least 1 hour.

25. An application of the cerium-zirconium solid solution according to claim 11, wherein the application is selected from any one of I or II: I. an application in catalytic conversion of one or more gases selected from CH.sub.4, C.sub.3H.sub.8, C.sub.2H.sub.6, NO.sub.2, NO, CO, H.sub.2O or CO.sub.2, II. an application in mobile source tail gas, waste gas treatment, natural gas catalytic combustion, organic waste gas purification or industrial waste gas denitration treatment.

26. An application of the catalyst according to claim 23, wherein the application is selected from any one of I or II: I. an application in catalytic conversion of one or more gases selected from CH.sub.4, C.sub.3H.sub.8, C.sub.2H.sub.6, NO.sub.2, NO, CO, H.sub.2O or CO.sub.2, II. an application in mobile source tail gas, waste gas treatment, natural gas catalytic combustion, organic waste gas purification or industrial waste gas denitration treatment.

Description

BRIEF DESCRIPTION OF FIGURES

[0057] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute an undue limitation on the present application. In the drawings:

[0058] FIG. 1 is the XPS spectrum of cerium-zirconium solid solution 1 #-1;

[0059] FIG. 2 is the XPS spectrum of cerium-zirconium solid solution 1 #-4;

[0060] FIG. 3 is the XPS spectrum of cerium-zirconium solid solution 1 #-8;

[0061] FIG. 4 is the XPS spectrum of cerium-zirconium solid solution 2 #-1;

[0062] FIG. 5 is the XPS spectrum of cerium-zirconium solid solution 2 #-4.

DETAILED DESCRIPTION

[0063] The present application will be described in detail below with reference to examples, but the present application is not limited to these examples.

[0064] Unless otherwise specified, the raw materials and catalysts in the examples of the present application are purchased through commercial channels.

[0065] The analysis methods in the examples of the present application are as follows:

[0066] 1. The instrument for detecting Ce.sup.3+/Ce.sup.4+ is the kratos-ultra DLD X-ray photoelectron spectrometer of Shimadzu Corporation.

[0067] 2. Micromeritics TriStar II automatic adsorption instrument of Micromeritics Corporation is used to analyze the specific surface of the cerium-zirconium solid solution.

[0068] 3. ChemBET-3000 instrument of Quantachrome Corporation is used to analyze the oxygen storage capacity of the cerium-zirconium solid solution.

[0069] 4. The catalyst evaluation instrument is Haina Chenke, HN-CK-21 infrared flue gas analyzer;

[0070] The catalytic evaluation adopts a method of simulating tail gas, and the air-fuel ratio λ is defined as: λ=(2V.sub.NO2+2.5V.sub.O2)/(2V.sub.CO+V.sub.C2H6), and V represents the final volume percentage of a mixed gas flowing through a catalyst bed; the carrier gas is Ar; the loading amount of the catalyst is 0.3 g, 40-60 mesh; the mass space velocity is 40000 h.sup.−1, and the test point temperature is 400° C.;

[0071] By controlling the percentage of gas, points around a theoretical air-fuel ratio of 1 are fluctuatedly taken to detect the effect of different Ce.sup.3−/Ce.sup.4+ ratios on catalytic reactions under different air-fuel ratios, and the value of k is: 0.9, 0.95, 1.0, 1.05, 1.10.

[0072] According to an embodiment of the present application, the preparation method for a cerium-zirconium solid solution includes the following steps:

[0073] 1) mixing: preparing trivalent cerium ions, tetravalent zirconium ions and other rare earth elements to obtain a clear aqueous solution as an initial mixture;

[0074] 2) Oxidation reaction:

[0075] {circle around (1)} Stirring the solution at a certain water bath temperature until it is clear, and adding an alkaline precipitant dropwise while stirring until the pH of the solution is 1.0-2.5, preferably 1.5-2.0; adding a certain amount of hydrogen peroxide with a mass concentration of 30% after the pH adjustment, and continuing to stir for 2-3 hours; introducing the solution into an autoclave and performing the hydrothermal reaction at 150-220° C. for 15-20 hours;

[0076] {circle around (2)} Adding a basic precipitation agent dropwise at a certain speed to the material after the second hydrothermal reaction until the pH is 8.0-10.0, preferably 8.5-9.5; aging the material after the pH adjustment at a certain water bath temperature for 3-4 hours;

[0077] 3) A first hydrothermal reaction: introducing the aged material into an autoclave, and performing the hydrothermal reaction at 180-220° C. for 10-20 hours; washing and drying the product after the reaction, and heat-treating under an inert atmosphere at 750° C.-850° C. for 4 hours to obtain a final product.

Example 1 Preparation of Cerium-Zirconium Solid Solution 1-1 # of Cerium, Zirconium, Lanthanum and Yttrium

[0078] Cerium-zirconium solid solution 1-1 # including cerium, zirconium, lanthanum and yttrium. The proportions of cerium oxide, zirconium oxide, lanthanum oxide, and yttrium oxide in cerium-zirconium solid solution 1 # according to the weights of the oxides are: 40 wt % cerium oxide, 50 wt % zirconium oxide, 5 wt % lanthanum oxide, 5 wt % yttrium oxide, with a total oxide concentration of 100 g/l.

[0079] The preparation method for cerium-zirconium solid solution 1 #-1 includes the following steps (the molar amount of hydrogen peroxide is 1.3 times the molar amount of Ce.sup.3+ ions):

[0080] 1) in the first beaker, 280 g of cerium nitrite corresponding to cerium oxide was dissolved in 500 mL of deionized water, and stirred for 1 hour; in the second beaker, 350 g of zirconium nitrate corresponding to zirconium oxide was added and dissolved with 1000 mL of deionized water, and stirred for 1 hour; in the third beaker, 35 g of lanthanum nitrate corresponding to lanthanum oxide and 35 g of yttrium nitrate corresponding to yttrium oxide were dissolved with 1000 mL of deionized water, and the solution was stirred until it was clear.

[0081] 2) The solutions in the three beakers were mixed and stirred until they were clear, and adjusted the pH to 2.0 with aqueous ammonia under a 40° C. water bath condition. At this time, the solution was a clear solution. 239.8 g of 30% hydrogen peroxide was added and stirred for 2 hours, and no precipitation was generated. The solution was set to 7 L, and introduced into a 10 L enamel hydrothermal synthesis kettle, the top of which was sealed with nitrogen. The reaction solution was subjected to the hydrothermal reaction at 180° C. for 20 hours. The product after the hydrothermal reaction was adjusted to pH 9-10 with aqueous ammonia, and the material after the pH adjustment was continued to be aged at 40° C. water bath temperature for 3 hours.

[0082] 3) The aged material was introduced into the autoclave, and subjected to the hydrothermal reaction at 180° C. for 10 hours; 300 g of lauric acid was added to the product after the reaction, stirred for 30 minutes, and then filtered with suction. The filter cake was dried at 120° C. for 5 hours, and then calcined at 750° C. for 5 hours to obtain the final product. During the drying and calcination process, all were protected with a nitrogen atmosphere to obtain cerium-zirconium solid solution 1-1 #.

Example 2 Preparation of Cerium-Zirconium Solid Solutions 1 #-2˜1 #-9 of Cerium, Zirconium, Lanthanum and Yttrium

[0083] According to the raw materials and preparation method for cerium-zirconium solid solution 1 #-1 of Example 1, cerium-zirconium solid solutions 1 #-2˜1 #-8 were prepared by changing the molar ratio of Ce.sup.3+ and hydrogen peroxide, respectively. The specific molar ratios of Ce.sup.3+/Ce.sup.4+ of cerium-zirconium solid solutions 1 #-1˜1 #-8 and obtained cerium-zirconium solid solutions 1 #-1˜1 #-8 are shown in Table 1.

[0084] According to the raw materials and preparation method for cerium-zirconium solid solution 1 #-1 of Example 1, the raw material Ce.sup.3+ was replaced with Ce.sup.4+, and hydrogen peroxide was not added in the step to obtain cerium-zirconium solid solution 1 #-9.

[0085] The molar ratio of Ce.sup.3+/Ce.sup.4+ was tested using XPS, in which the XPS spectra of cerium-zirconium solid solutions 1 #-1, 1 #-4, and 1 #-8 are shown in FIG. 1, FIG. 2, and FIG. 3 as examples to illustrate the test spectrum results of Ce.sup.3+/Ce.sup.4+. It can be seen from FIGS. 1-3 that the cerium-zirconium solid solutions 1 #-1, 1 #-4, and 1 #-8 simultaneously contain Ce.sup.3+/Ce.sup.4+ and their contents.

TABLE-US-00001 TABLE 1 cerium- cerium- cerium- cerium- cerium- cerium- cerium- cerium- cerium- zirconium zirconium zirconium zirconium zirconium zirconium zirconium zirconium zirconium solid solid solid solid solid solid solid solid solid solution solution solution solution solution solution solution solution solution Samples 1#-2 1#-2 1#-3 1#-4 1#-5 1#-6 1#-7 1#-8 1#-9 Molar 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0 ratio of hydrogen peroxide to Ce.sup.3+ Molar 0.142 0.156 0.162 0.278 0.397 0.462 0.668 0.793 0 ratio of Ce.sup.3+/Ce.sup.4+

Example 3 Preparation of Cerium-Zirconium Solid Solution 2 #-1 of Cerium, Zirconium, Lanthanum and Praseodymium

[0086] Cerium-zirconium solid solution 2 #-1 including cerium, zirconium, lanthanum and praseodymium. The proportions of cerium oxide, zirconium oxide, lanthanum oxide, and praseodymium oxide in cerium-zirconium solid solution 2 #-1 according to the weights of the oxides are: 20 wt % cerium oxide, 73 wt % zirconium oxide, 2 wt % lanthanum oxide, 5 wt % praseodymium oxide.

[0087] The preparation method for cerium-zirconium solid solution 2 #-1 includes the following steps (the molar amount of hydrogen peroxide is 1.3 times the molar amount of Ce.sup.3+ ions):

[0088] 1) in the first beaker, 140 g of cerium nitrite corresponding to cerium oxide was dissolved in 500 mL of deionized water, and stirred for 1 hour; in the second beaker, 511 g of zirconium nitrate corresponding to zirconium oxide was added and dissolved with 1000 mL of deionized water, and stirred for 1 hour; in the third beaker, 14 g of lanthanum nitrate corresponding to lanthanum oxide and 35 g of yttrium nitrate corresponding to yttrium oxide were dissolved with 1000 mL of deionized water, and the solution was stirred until it was clear.

[0089] 2) The solutions in the three beakers were mixed and stirred until they were clear, and adjusted the pH to 2.0 with aqueous ammonia in a 40° C. water bath. At this time, the solution was a clear solution. 119.9 g of 30% hydrogen peroxide was added and stirred for 2 hours, and no precipitation was generated. The solution was set to 7 L, and introduced into a 10 L enamel hydrothermal synthesis kettle, the top of which was sealed with nitrogen. The reaction solution was subjected to the hydrothermal reaction at 180° C. for 20 hours. The product after the hydrothermal reaction was adjusted to pH 9-10 with aqueous ammonia, and the material after the pH adjustment was aged at 40° C. water bath temperature for 3 hours.

[0090] 3) The aged material was introduced into the autoclave, and subjected to the hydrothermal reaction at 180° C. for 10 hours; 300 g of lauric acid was added to the product after the reaction, stirred for 30 minutes, and then filtered with suction. The filter cake was dried at 120° C. for 5 hours, and then calcined at 750° C. for 5 hours to obtain the final product. During the drying and calcination process, all were protected with a nitrogen atmosphere to obtain cerium-zirconium solid solution 2 #-1.

Example 4 Preparation of Cerium-Zirconium Solid Solutions 2 #-2˜2 #-8 of Cerium, Zirconium, Lanthanum and Yttrium

[0091] According to the raw materials and preparation method for cerium-zirconium solid solution 2 #-1 of Example 3, cerium-zirconium solid solutions 2 #-2˜2 #-8 were prepared by changing the molar ratio of Ce.sup.3+ and hydrogen peroxide, respectively. The specific molar ratios of Ce.sup.3+/Ce.sup.4+ of cerium-zirconium solid solutions 2 #-1˜2 #-8 and obtained cerium-zirconium solid solutions 2 #-1˜2 #-8 are shown in Table 2.

[0092] According to the raw materials and preparation method for cerium-zirconium solid solution 2 #-1 of Example 3, the raw material Ce′ is replaced with Ce′, and hydrogen peroxide was not added in the step to obtain cerium-zirconium solid solution 2 #-9.

[0093] The molar ratio of Ce.sup.3+/Ce.sup.4+ is tested using XPS, in which the XPS spectra of cerium-zirconium solid solutions 2 #-1 and 2 #-4 are shown in FIG. 4 and FIG. 5 as examples to illustrate the test spectrum results of Ce.sup.3+/Ce.sup.4+. It can be seen from FIGS. 4 and 5 that the cerium-zirconium solid solutions 2 #-1 and 2 #-4 simultaneously contain Ce.sup.3+/Ce.sup.4+ and their contents.

TABLE-US-00002 TABLE 2 cerium- cerium- cerium- cerium- cerium- cerium- cerium- cerium- cerium- zirconium zirconium zirconium zirconium zirconium zirconium zirconium zirconium zirconium solid solid solid solid solid solid solid solid solid solution solution solution solution solution solution solution solution solution Samples 2#-1; 2#-2; 2#-3; 2#-4; 2#-5; 2#-6; 2#-7; 2#-8; 2#-9; Molar 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0 ratio of hydrogen peroxide to Ce.sup.3+ Molar 0.139 0.161 0.172 0.269 0.406 0.462 0.650 0.811 0 ratio of Ce.sup.3+/Ce.sup.4+

Example 5 Specific Surface Area and Oxygen Storage Tests for Cerium-Zirconium Solid Solutions 1 #-1˜1 #-9 and 2 #-1˜2 #-9

[0094] The specific surface area of cerium-zirconium solid solutions 1 #-1˜1 #-8 and 2 #-1˜2 #-8 obtained in Examples 1-4, the specific surface area after aging at 1100° C. for 4 hours, the oxygen storage capacity by treatment at 750° C. for 4 hours and the oxygen storage capacity by treatment at 1100° C. for 4 hours were tested respectively, and the test results are shown in Table 3.

TABLE-US-00003 TABLE 3 Aging specific Specific surface area Oxygen storage Oxygen storage Test surface (m.sup.2/g)(1100° capacity/(μmol[O]/g) capacity/(μmol[O]/g) number Ce.sup.3+/Ce.sup.4+ area (m.sup.2/g) C.-4 h) (treated at 750° C.-4 h) (treated at 1100° C.-4 h) cerium- 0.142 76 40 623 591 zirconium solid solution 1#-1; cerium- 0.156 74 39 656 623 zirconium solid solution 1#-2 cerium- 0.162 78 41 618 603 zirconium solid solution 1#-3 cerium- 0.278 79 38 652 621 zirconium solid solution 1#-4 cerium- 0.397 77 37 599 576 zirconium solid solution 1#-5 cerium- 0.462 82 35 603 581 zirconium solid solution 1#-6 cerium- 0.668 85 30 578 556 zirconium solid solution 1#-7 cerium- 0.793 83 28 556 531 zirconium solid solution 1#-8 cerium- 0.021 84 31 612 582 zirconium solid solution 1#-9 cerium- 0.139 72 37 609 576 zirconium solid solution 2#-1; cerium- 0.161 71 37 597 569 zirconium solid solution 2#-2; cerium- 0.172 75 36 591 582 zirconium solid solution 2#-3; cerium- 0.269 79 38 600 579 zirconium solid solution 2#-4; cerium- 0.406 76 35 587 576 zirconium solid solution 2#-5; cerium- 0.462 74 35 561 549 zirconium solid solution 2#-6; cerium- 0.650 74 31 546 534 zirconium solid solution 2#-7; cerium- 0.811 80 27 521 509 zirconium solid solution 2#-8; cerium- 0.032 86 35 615 587 zirconium solid solution 2#-9;

[0095] It can be seen from Table 3 that cerium-zirconium solid solution 1 #-6 and cerium-zirconium solid solution 2 #-6 with the Ce.sup.3+/Ce.sup.4+ ratio between 0.1-0.5 have an oxygen storage capacity of not less than 561 μmol [O]/g after treatment at 750° C. for 4 hours; the specific surface area of cerium-zirconium solid solutions 1 #-6 and 2 #-6 treated at 1100° C. for 4 hours is not less than 35 m.sup.2/g. Cerium-zirconium solid solution 1 #-2 has an oxygen storage capacity of up to 656 μmol[O]/g after treatment at 750° C. for 4 hours; cerium-zirconium solid solution 1 #-1 has a specific surface area of up to 40 m.sup.2/g after treatment at 1100° C. for 4 hours. Cerium-zirconium solid solution 1 #-2 has an oxygen storage capacity of up to 623 μmol[O]/g after treatment at 1100° C. for 4 hours. Cerium-zirconium solid solution 1 #-6 and cerium-zirconium solid solution 2 #-6 with the ratio of Ce.sup.3+/Ce.sup.4+ between 0.1-0.5 show more excellent oxygen storage performance, indicating that they have more stable crystal structures.

Example 6 Preparation of Catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9

[0096] The catalytically active component palladium is loaded on the cerium-zirconium solid solution 1 #-1˜1 #-9, 2 #-1˜2 #-9 using the equal volume impregnation method to obtain catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9. Catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9 have the same palladium loading of 1.5 wt %.

[0097] Taking cerium-zirconium solid solution 1 #-1 as an example to illustrate the specific loading method, which includes: using chloropalladium acid solution (H.sub.2PdCl.sub.4) as a precursor impregnating solution, impregnating and loading cerium-zirconium solid solution 1 #-1 with a loading amount of 1.5 wt %; drying the loaded slurry in a rotary evaporator, then drying in a blast drying oven at 110° C. for 3 hours, and calcining in a calcining furnace at 500° C. for 3 hours under an air atmosphere.

Example 7 Catalytic Performance Tests of Catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9 for CO

[0098] Taking points at 400° C. and testing the conversion rates of catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9 for CO under different λ respectively as shown in Table 4. It can be seen from the data in Table 4 that when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.7, the catalyst has a high catalytic activity for CO; when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.5, the catalyst has a higher catalytic activity for CO; and the applicable λ range of the catalyst is wide.

TABLE-US-00004 TABLE 4 Test conversion rate of CO/% number Ce.sup.3+/Ce.sup.4+ λ = 1.1 λ = 1.05 λ = 1.0 λ = 0.95 λ = 0.9 Catalyst 1#-1 0.142 85.6 84.5 85.0 82.7 78.5 Catalyst 1#-2 0.156 91.8 90.5 89.6 88.6 84.9 Catalyst 1#-3 0.162 97.2 96.4 96.0 95.8 92.8 Catalyst 1#-4 0.278 98.6 97.1 96.8 95.3 93.4 Catalyst 1#-5 0.397 99.1 98.6 97.1 96.5 94.2 Catalyst 1#-6 0.462 98.1 96.3 95.2 94.5 91.8 Catalyst 1#-7 0.668 90.2 89.8 82.6 81.9 76.1 Catalyst 1#-8 0.793 85.2 84.4 79.3 77.6 73.7 Catalyst 1#-9 0.021 82.3 81.6 78.9 77.2 77.8 Catalyst 2#-1 0.139 91.4 90.7 90.6 88.4 79.7 Catalyst 2#-2 0.161 92.3 93.5 92.8 91.9 85.6 Catalyst 2#-3 0.172 96.5 95.9 94.0 93.5 89.3 Catalyst 2#-4 0.269 98.9 97.2 96.3 95.7 90.7 Catalyst 2#-5 0.406 96.5 96.7 96.7 96.4 90.4 Catalyst 2#-6 0.462 93.7 92.4 91.8 90.7 87.4 Catalyst 2#-7 0.650 89.1 87.6 85.4 80.9 79.3 Catalyst 2#-8 0.811 84.3 82.3 81.1 80.4 75.9 Catalyst 2#-9 0.032 82.6 81.4 80.3 79.7 78.4

Example 8 Catalytic Performance Tests of Catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9 for C.SUB.2.H.SUB.6

[0099] Taking points at 400° C. and testing the conversion rates of catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9 for C.sub.2H.sub.6 under different λ respectively as shown in Table 5. It can be seen from the data in Table 5 that when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.7, the catalyst has a high catalytic activity for C.sub.2H.sub.6; when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.5, the catalyst has a higher catalytic activity for C.sub.2H.sub.6; and the applicable λ range of the catalyst is wide.

TABLE-US-00005 TABLE 5 Test conversion rate of C.sub.2H.sub.6 number Ce.sup.3+/Ce.sup.4+ λ = 1.1 λ = 1.05 λ = 1.0 λ = 0.95 λ = 0.9 Catalyst 1#-1 0.142 84.3 83.2 84.0 83.2 81.7 Catalyst 1#-2 0.156 86.9 85.7 87.2 82.9 82.7 Catalyst 1#-3 0.162 96.1 96.9 95.9 94.6 93.8 Catalyst 1#-4 0.278 97.8 97.5 97.3 96.8 95.1 Catalyst 1#-5 0.397 98.6 98.1 98.2 97.9 94.2 Catalyst 1#-6 0.462 94.5 95.0 94.5 93.8 91.8 Catalyst 1#-7 0.668 86.4 86.4 85.3 83.1 91.8 Catalyst 1#-8 0.793 82.2 81.8 80.6 79.2 74.2 Catalyst 1#-9 0.021 75.2 74.1 73.4 73.7 72.4 Catalyst 2#-1 0.139 85.0 84.3 83.0 81.5 81.9 Catalyst 2#-2 0.161 87.4 85.7 85.2 83.1 83.5 Catalyst 2#-3 0.172 96.4 97.2 96.4 93.9 94.1 Catalyst 2#-4 0.269 97.1 97.6 97.7 97.1 95.7 Catalyst 2#-5 0.406 98.9 99.5 98.2 98.1 93.7 Catalyst 2#-6 0.462 95.2 94.8 94.9 94.6 91.7 Catalyst 2#-7 0.650 86.6 87.1 84.8 83.5 92.1 Catalyst 2#-8 0.811 83.1 82.8 81.6 79.7 74.8 Catalyst 2#-9 0.032 77.6 76.4 75.3 74.8 73.7

Example 9 Catalytic Performance Tests of Catalysts 1 #-1˜1 #-8 and 2 #-1˜2 #-8 for NO.SUB.2

[0100] Taking points at 400° C. and testing the conversion rates of catalysts 1 #-1˜1 #-9 and 2 #-1˜2 #-9 for NO.sub.2 under different λ respectively as shown in Table 6. It can be seen from the data in Table 6 that when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.7, the catalyst has a high catalytic activity for NO.sub.2; when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.5, the catalyst has a higher catalytic activity for NO.sub.2; and the applicable λ range of the catalyst is wide.

TABLE-US-00006 TABLE 6 Test conversion rate of NO.sub.2 number Ce.sup.3+/Ce.sup.4+ λ = 1.1 λ = 1.05 λ = 1.0 λ = 0.95 λ = 0.9 Catalyst 1#-1 0.142 66.3 70.2 73.6 78.7 85.4 Catalyst 1#-2 0.156 67.4 72.2 75.2 80.9 89.7 Catalyst 1#-3 0.162 79.5 81.3 84.8 86.4 93.6 Catalyst 1#-4 0.278 85.6 87.6 89.5 94.3 97.4 Catalyst 1#-5 0.397 87.8 87.4 88.9 94.9 98.2 Catalyst 1#-6 0.462 84.7 83.1 87.4 92.7 97.8 Catalyst 1#-7 0.668 77.5 76.5 79.8 85.3 87.4 Catalyst 1#-8 0.793 74.6 73.8 76.5 78.9 82.6 Catalyst 1#-9 0.021 62.1 69.7 71.4 75.6 85.2 Catalyst 2#-1 0 67.5 71.7 74.6 79.7 87.2 Catalyst 2#-2 0.139 68.5 73.2 76.7 83.9 90.7 Catalyst 2#-3 0.161 80.1 84.3 85.9 88.2 95.8 Catalyst 2#-4 0.172 83.6 90.1 90.1 96.1 98.4 Catalyst 2#-5 0.269 89.8 88.7 92.3 95.1 99.3 Catalyst 2#-6 0.406 84.9 83.4 87.7 93.6 96.6 Catalyst 2#-7 0.462 77.8 77.3 82.4 87.1 92.1 Catalyst 2#-8 0.650 64.4 69.4 75.4 79.6 88.7 Catalyst 2#-9 0.032 75.2 74.3 73.6 72.1 70.8

Example 10 Preparation of Aged Catalysts 1 #-1˜1 #-8

[0101] After aging cerium-zirconium solid solutions 1 #-1˜1 #-8 at 1100° C. for 4 hours, aged cerium-zirconium solid solutions 1 #-1˜1 #-8 are obtained. Aged catalysts 1 #-1˜1 #-8 are obtained by loading the same amount of palladium on aged cerium-zirconium solid solutions 1 #-1˜1 #-8 using the loading method of Example 6.

Example 11 Catalytic Performance Tests of Aged Catalysts 1 #-1˜1 #-8 for NO.SUB.2

[0102] Taking points at 400° C. The conversion rates of aged catalysts 1 #-1˜1 #-8 for NO.sub.2 under different λ respectively are as shown in Table 7. It can be seen from the data in Table 7 that when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.7, the aged catalysts 1 #-1˜1 #-8 have a high catalytic activity for NO.sub.2; when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.5, the aged catalysts 1 #-1˜1 #-8 have a higher catalytic activity for NO.sub.2, indicating that when the ratio of Ce.sup.3+/Ce.sup.4+ is between 0.1-0.5, they show better structural stability.

TABLE-US-00007 TABLE 7 Test conversion rate of NO.sub.2 number Ce.sup.3+/Ce.sup.4+ λ = 1.1 λ = 1.05 λ = 1.0 λ = 0.95 λ = 0.9 Aged catalyst 1#-1 0.142 60.8 64.4 66.7 70.1 75.2 Aged catalyst 1#-2 0.156 61.3 63.6 67.9 72.3 76.4 Aged catalyst 1#-3 0.162 73.4 74.2 77.8 78.5 79.2 Aged catalyst 1#-4 0.278 75.7 76.8 77.8 77.3 80.2 Aged catalyst 1#-5 0.397 74.8 79.5 82.5 86.9 92.7 Aged catalyst 1#-6 0.462 75.9 80.1 83.7 88.7 93.6 Aged catalyst 1#-7 0.668 72.3 77.6 78.9 82.3 85.7 Aged catalyst 1#-8 0.793 70.6 72.8 74.8 75.9 78.9 Aged catalyst 1#-9 0.021 62.7 63.8 62.7 64.9 69.7

[0103] The above is only the embodiments of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the application shall be included in the protection scope of the application.